One way that you can improve your app is by having vocal announcements that announce each dance, and invite dancers to take their place on the floor. I've found soundbytes from various competition videos posted on YouTube by ParadigmDVD, and the dancers on my team love having an actual emcee direct the rounds practice.

Just simple phrases like "And your 1st dance: The Waltz", "Music Please", and "Thank you Competitors, please take your places for your 2nd dance: The Tango".